L-dopa, L-3,4-dihydroxyphenyl alanine, or 3-(3,4-dihydroxy-phenyl)-L-alanine, or 3-hydroxy-L-tyrosine, alternatively, is a pharmaceutically active compound, which is active at the inhibition of symptoms of the Parkinsons disease, particularly at the inhibition of the tremor related to the Parkinsons disease.
However, hitherto has no pharmaceutical composition been developed which gives a satisfactory pharmacological effect, i.e., a pharmaceutically high, even plasma level. This depends on several factors, i.a., that L-dopa is rapidly decomposed by carboxylic elimination. This can, and has been regulated by adding a decarboxylase inhibitor, such as benserazide or carbidopa, the administration of which means that the L-dopa dose can be considerably reduced. Other problems are that L-dopa is resorbed over a restricted part of the gastro-intestinal tract, i.e., shows a so called absorption window. Hitherto it has been necessary to administer known compositions five to eight times per 24 hrs due to the short half life time of L-dopa. In spite of this the treatment has given high top levels in the plasma which in turn leads to troublesome side-effects.